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Hough Tool

This tool helps you to familiarize yourself with Hough space - the result of the Hough Transform:  Filter / Hough Transform.  Click on the image, or on the Hough transform, and see the corresponding line or curve in the other image.

Orig Im Select Original Image.
Hough xfm Select Hough transform image.
Line color! Lines and sinusoids are drawn in this color. Click to change to the menu selected color:
Hough Click If ON, click and drag on Hough Xfm, see corresponding line on Original image. Draws line with line color on mouse up.
Orig Click If ON, click and drag on Original image, see sinusoid on Hough Xfm image. Draws sinusoid with line color on mouse up.
Square Gratings Types line spacings in each direction and the angle between them.  See example.
Spot R! Vertical halfwidth of spot.  (Approximate - this sets the region for the measurements.)
Min Pct! Estimate of minimum distance between spots.



Description of Hough Transform

The Linear Hough Transform is often represented this way:

where r (rho) and theta are the distance and inclination of a line in the image (below, left).  Thus, in Hough space (below, right), the line corresponds to a single point.

The Linear Hough Transform maps straight lines into points. Points are easier to locate (to blob) than are lines, using image processing techniques.